#include <GLUT/glut.h>

class Vec3f{
public:
    Vec3f(GLfloat x, GLfloat y, GLfloat z)
    {
        _Data[0] = x;
        _Data[1] = y;
        _Data[2] = z;
    }

    const GLfloat *getdata(void) const
    {
        return _Data;
    }

    Vec3f operator+(const Vec3f& Right) const
    {
        return Vec3f(_Data[0] + Right._Data[0],
            _Data[1] + Right._Data[1],
            _Data[2] + Right._Data[2]);
    }
    Vec3f operator*(const GLfloat& Right) const
    {
        return Vec3f(_Data[0] * Right,
            _Data[1] * Right,
            _Data[2] * Right);
    }
private:
    GLfloat _Data[3];
};

class SceneManager
{
protected:
    GLenum _DrawPrimitiveType;
    GLfloat _Translation[3];
    GLfloat _Rotation[3];
	unsigned int _Example;
	bool _EnableBlending;

public:
    SceneManager(void) : _DrawPrimitiveType(GL_POINTS),_Example(1),_EnableBlending(false)
    {
        _Rotation[0] = _Rotation[1] = _Rotation[2] = 0.0f;
        _Translation[0] = _Translation[1] = 0.0f;
        _Translation[2] = -4.0f;
    }

    void init(void)
    {
		glEnable(GL_DEPTH_TEST);
		//glEnable(GL_CULL_FACE);
		//glCullFace(GL_BACK);
		
        glLineWidth(3.0f);
        glPointSize(18.0f);
		glClearColor(0.0,0.0,0.0,0.0);
    }

    void reshape(int w, int h)
    {
        glViewport(0,0,w,h);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        gluPerspective(60.0f,static_cast<GLfloat>(w)/static_cast<GLfloat>(h),.1f,100.0f);
        glMatrixMode(GL_MODELVIEW);
        glutPostRedisplay();
    }
	
    void display(void)
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		
		glMatrixMode(GL_MODELVIEW);
        glPushMatrix();
		
        glTranslatef(_Translation[0], _Translation[1], _Translation[2]);
        glRotatef(_Rotation[0],1.0f,0.0f,0.0f);
        glRotatef(_Rotation[1],0.0f,1.0f,0.0f);
        glRotatef(_Rotation[2],0.0f,0.0f,1.0f);
		
		switch(_Example)
		{
			case 4:
				antialiasPolygons();
				break;
			case 3:
				antialiasPointsExample();
				break;
			case 2:
				antialiasLinesExample();
				break;
			case 1:
			default:
				transparencyExample();
				break;
		}
		
        glPopMatrix();
        glutSwapBuffers();
	}
	
    void transparencyExample(void)
    {
		
        Vec3f origin(0.0,0.0,0.0);
        drawAxis(origin,Vec3f(1.0,0.0,0.001), Vec3f(1.0,0.0,0.001),2.0f);
        drawAxis(origin,Vec3f(0.0,1.0,0.001), Vec3f(0.0,1.0,0.001),2.0f);
        drawAxis(origin,Vec3f(0.0,0.0,1.0), Vec3f(0.0,0.0,1.0),2.0f);
		
		if(_EnableBlending)
		{
			glEnable(GL_BLEND);
		}
		else
		{
			glDisable(GL_BLEND);
		}

		glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
		
		GLfloat size(1.0);
        glBegin(GL_QUADS);
			//Green Square
			glColor4f(0.0,1.0,0.0,0.5);
			glVertex3f(-size, size, -size);
			glVertex3f(-size, -size, -size);
			glVertex3f(size, -size, -size);
			glVertex3f(size, size, -size);
			
			//Blue Square
			glColor4f(0.0,0.0,1.0,0.5);
			glVertex3f(-size, size, 0.0f);
			glVertex3f(-size, -size, 0.0f);
			glVertex3f(size, -size, 0.0f);
			glVertex3f(size, size, 0.0f);
		
			//Red Square
			glColor4f(1.0,0.0,0.0,0.5);
			glVertex3f(-size, size, size);
			glVertex3f(-size, -size, size);
			glVertex3f(size, -size, size);
			glVertex3f(size, size, size);
		
        glEnd();
    }
	
	void antialiasLinesExample(void)
	{
		glEnable(GL_LINE_SMOOTH);
		if(_EnableBlending)
		{
			glEnable(GL_BLEND);
		}
		else
		{
			glDisable(GL_BLEND);
		}
		glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
		
		GLfloat size(1.0);
        glBegin(GL_LINES);
		//Green Square
		glColor4f(0.0,1.0,0.0,1.0);
		glVertex3f(-size, size, -size);
		glVertex3f(-size, -size, -size);
		glVertex3f(size, -size, -size);
		glVertex3f(size, size, -size);
		
		//Blue Square
		glColor4f(0.0,0.0,1.0,1.0);
		glVertex3f(-size, size, 0.0f);
		glVertex3f(-size, -size, 0.0f);
		glVertex3f(size, -size, 0.0f);
		glVertex3f(size, size, 0.0f);
		
		//Red Square
		glColor4f(1.0,0.0,0.0,1.0);
		glVertex3f(-size, size, size);
		glVertex3f(-size, -size, size);
		glVertex3f(size, -size, size);
		glVertex3f(size, size, size);
		
        glEnd();
	}
	
	void antialiasPointsExample(void)
	{
		glEnable(GL_POINT_SMOOTH);
		if(_EnableBlending)
		{
			glEnable(GL_BLEND);
		}
		else
		{
			glDisable(GL_BLEND);
		}
		glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
		
		GLfloat size(1.0);
        glBegin(GL_POINTS);
		//Green Square
		glColor4f(0.0,1.0,0.0,1.0);
		glVertex3f(-size, size, -size);
		glVertex3f(-size, -size, -size);
		glVertex3f(size, -size, -size);
		glVertex3f(size, size, -size);
		
		//Blue Square
		glColor4f(0.0,0.0,1.0,1.0);
		glVertex3f(-size, size, 0.0f);
		glVertex3f(-size, -size, 0.0f);
		glVertex3f(size, -size, 0.0f);
		glVertex3f(size, size, 0.0f);
		
		//Red Square
		glColor4f(1.0,0.0,0.0,1.0);
		glVertex3f(-size, size, size);
		glVertex3f(-size, -size, size);
		glVertex3f(size, -size, size);
		glVertex3f(size, size, size);
		
        glEnd();
	}
	
    void antialiasPolygons(void)
    {
		
		if(_EnableBlending)
		{
			glEnable(GL_BLEND);
			glDisable(GL_DEPTH_TEST);
		}
		else
		{
			glDisable(GL_BLEND);
			glEnable(GL_DEPTH_TEST);
		}
		glHint(GL_POLYGON_SMOOTH_HINT,GL_NICEST);
		glEnable(GL_POLYGON_SMOOTH);
		
		glBlendFunc(GL_SRC_ALPHA_SATURATE,GL_ONE);
		
		GLfloat size(1.0);
        glBegin(GL_QUADS);
		//Green Square
		glColor4f(0.0,1.0,0.0,1.0);
		glVertex3f(-size, size, -size);
		glVertex3f(-size, -size, -size);
		glVertex3f(size, -size, -size);
		glVertex3f(size, size, -size);
		
		//Blue Square
		glColor4f(0.0,0.0,1.0,1.0);
		glVertex3f(-size, size, 0.0f);
		glVertex3f(-size, -size, 0.0f);
		glVertex3f(size, -size, 0.0f);
		glVertex3f(size, size, 0.0f);
		
		//Red Square
		glColor4f(1.0,0.0,0.0,1.0);
		glVertex3f(-size, size, size);
		glVertex3f(-size, -size, size);
		glVertex3f(size, -size, size);
		glVertex3f(size, size, size);
		
        glEnd();
    }

    void drawAxis(Vec3f origin, Vec3f direction, Vec3f color, GLfloat Length)
    {
        glBegin(GL_LINES);
            glColor3fv(color.getdata());
            glVertex3fv(origin.getdata());
            Vec3f v(origin + (direction * Length));
            glVertex3fv(v.getdata());
        glEnd();
    }
    
    void keyboard(unsigned char key, int x, int y)
    {
        switch(key)
        {
        case 'a':
            _Rotation[1] -= 3.5;
            break;
        case 'd':
            _Rotation[1] += 3.5;
            break;
        case 'w':
            _Rotation[0] -= 3.5;
            break;
        case 's':
            _Rotation[0] += 3.5;
				break;
		case 'z':
				_EnableBlending = !_EnableBlending;
			break;
				
			case '1':
				_Example = 1;
				break;
			case '2':
				_Example = 2;
				break;
			case '3':
				_Example = 3;
				break;
			case '4':
				_Example = 4;
				break;
        }
        glutPostRedisplay();
    }
};

SceneManager mgr;

void reshape(int w, int h)
{
    mgr.reshape(w,h);
}

void display(void)
{
    mgr.display();
}
void keyboard(unsigned char key, int x, int y)
{
    mgr.keyboard(key,x,y);
}

int
main(int argc, char **argv)
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH | GLUT_ALPHA);
	glutCreateWindow("Double Buffering");
  glutDisplayFunc(display);
  glutReshapeFunc(reshape);
  glutKeyboardFunc(keyboard);
  glutReshapeWindow(800,600);
  mgr.init();
  glutMainLoop();
  return 0;             /* ANSI C requires main to return int. */
}